Transmission Conversion

[buster brown]

I Have a 1989z71 w/ 5-speed. I want to replace trans w/ 700r4. I can do the work myself but would like some guidelines? Is there any info anywhere that would be specific to this task?

[broughy84]

You would need an automatic radiator, all the linkage for the auto, and an Automatic steering column. Everything else should work.

[2000CAYukon]

In addition, you may need the PROM for an automatic since the PCM controls the TCC locking up. If you don't want to change the PROM, you can get vacuum switch to control TCC lockup.

A TV Cable is a must. Not sure if your TBI has the mounting bracket for it. If not, you should be able to get one from a boneyard.

//2000CAYukon

[buster brown]

I think I have all the parts. The tranny has a kickdown cable that mounts to the throttle body. Would I still need a vacuum switch?

[buster brown]

Also, I have an automatic steering column, but I was wanting to use a floor shifter. The hole is already there. Can u recommend a good simple shifter?

[2000CAYukon]

Originally Posted by buster brown

I think I have all the parts. The tranny has a kickdown cable that mounts to the throttle body. Would I still need a vacuum switch?

For the 700R4, it is not really a kickdown cable since the TV controls shift timing in the 700R4 not just downshifting.

TCC lockup is not controlled by the TV Cable so you either need to use a PROM from an automatic along with the correct wiring of the TCC lockup. If you don't want to go that route, then you should use a vacuum switch to control lockup. With the price of gas these days, you will want the lockup function especially on the freeway. If you are not going to drive it much on the freeway, then you might be able to get away without TCC lockup.

//2000CAYukon

[2000CAYukon]

Originally Posted by buster brown

Also, I have an automatic steering column, but I was wanting to use a floor shifter. The hole is already there. Can u recommend a good simple shifter?

You will need something from the aftermarket. Lokar comes to mind, see http://www.jegs.com/p/Lokar/751162/10002/-1/10517

//2000CAYukon

[silicon212]

Originally Posted by 2000CAYukon

For the 700R4, it is not really a kickdown cable since the TV controls shift timing in the 700R4 not just downshifting.

TCC lockup is not controlled by the TV Cable so you either need to use a PROM from an automatic along with the correct wiring of the TCC lockup. If you don't want to go that route, then you should use a vacuum switch to control lockup. With the price of gas these days, you will want the lockup function especially on the freeway. If you are not going to drive it much on the freeway, then you might be able to get away without TCC lockup.

//2000CAYukon

You can get away without lockup AS LONG as you're not in OD! Even in the city, driving in OD with no lockup will result in the destruction of the 3-4 clutch.

One question though, if the truck came factory with a 5-spd, is it even going to have the TCC hookup on the ECM cable?

[2000CAYukon]

Originally Posted by silicon212

You can get away without lockup AS LONG as you're not in OD! Even in the city, driving in OD with no lockup will result in the destruction of the 3-4 clutch.

One question though, if the truck came factory with a 5-spd, is it even going to have the TCC hookup on the ECM cable?

I am not sure if there is a hookup or not in the ECM cable but I would think you could make that work. By the way, my 90 GMC K1500 700R4 locks up the TCC in both 3rd and 4th gear.

//2000CAYukon

[silicon212]

As does the transmission in my Caprice. I like it better that way, gasoline sure is expensive these days ...

[2000CAYukon]

Originally Posted by silicon212

As does the transmission in my Caprice. I like it better that way, gasoline sure is expensive these days ...

Nice looking 9C1! Did you beef up the 700R4 at all?

//2000CAYukon

[silicon212]

Originally Posted by 2000CAYukon

Nice looking 9C1! Did you beef up the 700R4 at all?

//2000CAYukon

I put a stiffer 1-2 accumulator spring in it, and modified the pressure regulator in the front pump but aside from that, it's pretty much stock.

BTW, thanks for the compliment on the car! However, it's undergoing yet another repaint. The red paint is damaged beyond hope due to a FUBAR on my part when I sprayed it.

[2000CAYukon]

Originally Posted by silicon212

I put a stiffer 1-2 accumulator spring in it, and modified the pressure regulator in the front pump but aside from that, it's pretty much stock.

I have the Transgo Jr Kit along with the Vette Servo in mine. Of course, my engine is stock and no where near the power that your LM1 is putting out.

//2000CAYukon

[buster brown]

Thanks for the info 212 and yukon. Nice car silicon. I'll keep you posted.